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      1 // Copyright 2016 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef MOJO_PUBLIC_CPP_BINDINGS_SYNC_HANDLE_REGISTRY_H_
      6 #define MOJO_PUBLIC_CPP_BINDINGS_SYNC_HANDLE_REGISTRY_H_
      7 
      8 #include <unordered_map>
      9 
     10 #include "base/callback.h"
     11 #include "base/macros.h"
     12 #include "base/memory/ref_counted.h"
     13 #include "base/threading/thread_checker.h"
     14 #include "mojo/public/cpp/bindings/bindings_export.h"
     15 #include "mojo/public/cpp/system/core.h"
     16 
     17 namespace mojo {
     18 
     19 // SyncHandleRegistry is a thread-local storage to register handles that want to
     20 // be watched together.
     21 //
     22 // This class is not thread safe.
     23 class MOJO_CPP_BINDINGS_EXPORT SyncHandleRegistry
     24     : public base::RefCounted<SyncHandleRegistry> {
     25  public:
     26   // Returns a thread-local object.
     27   static scoped_refptr<SyncHandleRegistry> current();
     28 
     29   using HandleCallback = base::Callback<void(MojoResult)>;
     30   bool RegisterHandle(const Handle& handle,
     31                       MojoHandleSignals handle_signals,
     32                       const HandleCallback& callback);
     33 
     34   void UnregisterHandle(const Handle& handle);
     35 
     36   // Waits on all the registered handles and runs callbacks synchronously for
     37   // those ready handles.
     38   // The method:
     39   //   - returns true when any element of |should_stop| is set to true;
     40   //   - returns false when any error occurs.
     41   bool WatchAllHandles(const bool* should_stop[], size_t count);
     42 
     43  private:
     44   friend class base::RefCounted<SyncHandleRegistry>;
     45 
     46   struct HandleHasher {
     47     size_t operator()(const Handle& handle) const {
     48       return std::hash<uint32_t>()(static_cast<uint32_t>(handle.value()));
     49     }
     50   };
     51   using HandleMap = std::unordered_map<Handle, HandleCallback, HandleHasher>;
     52 
     53   SyncHandleRegistry();
     54   ~SyncHandleRegistry();
     55 
     56   HandleMap handles_;
     57 
     58   ScopedHandle wait_set_handle_;
     59 
     60   base::ThreadChecker thread_checker_;
     61 
     62   DISALLOW_COPY_AND_ASSIGN(SyncHandleRegistry);
     63 };
     64 
     65 }  // namespace mojo
     66 
     67 #endif  // MOJO_PUBLIC_CPP_BINDINGS_SYNC_HANDLE_REGISTRY_H_
     68